Absorption of Na+ and K+ ions does not occur in Bowman's capsule.

Bowman's capsule is the initial part of the nephron in the kidney. It is responsible for the first step in the process of urine formation, known as glomerular filtration. During glomerular filtration, blood pressure forces fluid and small molecules (including Na+ and K+ ions) from the glomerulus into the Bowman's capsule. However, absorption of these ions does not occur in the Bowman's capsule. Here's why:

1. Glomerular Filtration:
- The glomerulus is a network of capillaries located within the Bowman's capsule. It acts as a filtration unit in the kidney.
- Blood pressure forces plasma and small molecules, including Na+ and K+ ions, through the capillary walls and into the Bowman's capsule.
- This process is non-selective and allows the formation of a filtrate containing water, ions, waste products, and other small molecules.

2. Proximal Convoluted Tubule (PCT):
- After the filtrate is formed in the Bowman's capsule, it flows into the proximal convoluted tubule (PCT).
- The PCT is the first segment of the renal tubule where reabsorption of various substances occurs.
- In the PCT, around 65% to 70% of the filtered Na+ and K+ ions are actively reabsorbed into the bloodstream.
- This reabsorption is crucial for maintaining electrolyte balance and regulating blood volume and blood pressure.

3. Loop of Henle:
- The filtrate then moves from the PCT to the loop of Henle, which consists of a descending and ascending limb.
- In the loop of Henle, water and certain ions (including Na+ and K+ ions) are reabsorbed to varying degrees, depending on the osmolarity of the surrounding fluid.
- The reabsorption of Na+ and K+ ions in the loop of Henle is important for establishing the concentration gradient necessary for the reabsorption of water in the collecting duct.

4. Distal Convoluted Tubule (DCT):
- After the loop of Henle, the filtrate enters the distal convoluted tubule (DCT).
- In the DCT, further reabsorption of Na+ and K+ ions occurs, regulated by hormones such as aldosterone and antidiuretic hormone (ADH).
- The DCT plays a role in fine-tuning the reabsorption of these ions based on the body's needs.

5. Collecting Duct:
- Finally, the filtrate enters the collecting duct, where further reabsorption and concentration of urine occur.
- The collecting duct is also influenced by hormones, particularly ADH, which regulates the reabsorption of water.

In conclusion, absorption of Na+ and K+ ions does not occur in Bowman's capsule. Rather, significant reabsorption of these ions takes place in the proximal convoluted tubule, loop of Henle, distal convoluted tubule, and collecting duct.